Method for manufacturing a three-dimensionally deformable, sheet-like reinforcing structure

ABSTRACT

A method for manufacturing a three-dimensionally deformable, sheet-like reinforcing structure, wherein material attenuations ( 3 ) are incorporated into a sheet-like, cellular base material, distributed over an area of the base material, by means of cutting or sawing, said material attenuations ( 3 ) sub-dividing the base material into a plurality of material cells ( 1 ) which are delineated from each other by the material attenuations ( 3 ) but are still connected to each other.

CROSS-REFERENCE TO PRIOR APPLICATION

This application is a national stage filing (35 U.S.C. 371) ofPCT/EP2007/062099, filed on 8 November 2007.

FIELD OF THE INVENTION

The invention relates to a method for manufacturing athree-dimensionally deformable, sheet-like reinforcing structure from alikewise sheet-like, cellular base material. The base material can inparticular be a foamed plastic which is reinforced with reinforcingstructures or also a non-reinforced foamed plastic. The invention alsorelates to a reinforcing structure manufactured in accordance with themethod, and to its use for manufacturing a composite material, a“composite”, for which the reinforcing structure serves as a corematerial.

BACKGROUND OF THE INVENTION

Cellular reinforcing structures and their use as core materials ofcomposites is known from WO 98/10919 A2. The reinforcing structures arearranged between covering layers of the respective composite in asandwich construction, for manufacturing light but nonetheless rigidcomposites. The reinforcing structures serve as spacers for the coveringlayers and increase the bending and buckling resistance of thecomposites. In order to be able to fixedly connect the covering layersof a composite, between which a reinforcing structure is inserted, toeach other by means of a joiner, for example by means of an adhesive orsynthetic resin, a honeycombed reinforcing structure is used comprisinghexagonal material cells and thin bridges which connect them to eachother. The joiner penetrates the cavities of the reinforcing structurebetween the material cells in the region of the bridges, such that atleast in the region of the cavities, a material connection to thecovering layers is guaranteed. The structuring into material cells andconnecting bridges provides the reinforcing structure with a flexibilitysuch as is needed for manufacturing three-dimensionally deformedcomposites.

However, producing the cavities or other types of material attenuationsto the required precision and a desirable efficiency is problematic.Precisely incorporating the material attenuations, for example by meansof milling, laser treatment or water jet treatment, is verytime-consuming and therefore cost-intensive.

SUMMARY OF THE INVENTION

It is an object of the invention to precisely and efficientlymanufacture reinforcing structures of the type cited.

The subject of the invention is a method for manufacturing athree-dimensionally deformable, sheet-like reinforcing structure,wherein material attenuations are incorporated or machined or workedinto a sheet-like, cellular base material, distributed over the area ofthe base material, said material attenuations sub-dividing the basematerial into a plurality of material cells which are delineated fromeach other by the material attenuations but are still connected to eachother. The material cells are formed by the cellular base material. Thematerial attenuations are preferably incorporated in a regulardistribution, such that a correspondingly regular distribution of thematerial cells and thus structuring of the reinforcing structures isobtained. The material cells preferably each exhibit the same shape andsize. The same preferably applies to the material attenuations. Thematerial cells can in particular be polygons, preferably equilateralpolygons. They are preferably hexagonal in a top view onto thereinforcing structure.

When incorporating the material attenuations in a batch operation, thebase material can be provided in the form of board material which can inparticular be plate-like or, in more flexible boards, also mat-like.Flexible base material can also be provided with the materialattenuations as a web product in a continuous method. The base materialcan exhibit a thickness of a few millimetres, for example at least 5 mm,and a thickness of up to a few centimetres, preferably at most 20 mm.The cellular material can have a predominantly open porosity, or morepreferably a closed porosity, in order to prevent water or even moisturefrom entering.

Foamed plastic materials are preferred base materials, wherein foamedthermoplasts or also foamed thermosets can in particular be used.Advantageous plastic foam materials are thus for example polyethyleneterephthalate (PET) foams or polystyrene (PS) foams, as well as moreflexible polyethylene (PE) foams or polypropylene (PP) foams or also, asan example of a thermosetting material, polyurethane (PUR) foams. Theplastic foam material can be reinforced, i.e. can comprise reinforcingstructures embedded in the foam material, or can be used with noreinforcement. The base material is preferably extruded andsimultaneously foamed.

In accordance with the invention, the material attenuations areincorporated into the base material by means of cutting or sawing. Theword “or” is used here, as elsewhere in accordance with the invention,always in its usual logical sense, i.e. it includes the meaning of“either . . . or” and also the meaning of “and”, providing therespective context does not rule out any of these meanings. Accordingly,the material attenuations can be incorporated solely by cutting orsolely by sawing or—as corresponds to preferred method embodiments—by amulti-stage process which includes cutting and sawing and preferablyconsists of cutting and sawing.

In a preferred multi-stage incorporating process, the first stageinvolves cutting in accordance with the shape of the materialattenuations, and after the cutting process, which itself can compriseone or more stages, sawing in accordance with the shape of the materialattenuations. The material attenuations are sawn out.

Although the material attenuations can be incorporated in the form ofrecesses, material attenuations which are shaped as passages, i.e.cavities extending from the upper to the lower side of the reinforcingstructure, are preferred, since material attenuations extending throughthe structure are advantageous with regard to three-dimensionaldeformability. When manufacturing a composite, the reinforcing structurecan be penetrated in the region of the passages by a free-flowingjoiner, in order to connect the covering layers of the composite to eachother through the reinforcing structure in a material connection.

After the material attenuations have been incorporated, material webs orbridges remain which connect the material cells to each other. Aftercutting or sawing—preferably, after the final cutting or sawingstep—these connecting bridges are compressed, thus permanently reducingtheir cross-section. The cellular base material is compacted in theregion of the bridges. The bridges advantageously fall short of an upperside and lower side of the reinforcing structure, such that when thereinforcing structure is embedded between two covering layers, forexample two metallic or plastic covering layers, the bridges do nottouch said covering layers. Compacting the bridges by compression is aninexpensive way of making the bridges short of the upper and lower sideof the reinforcing structure. When the reinforcing structure is insertedbetween covering layers of a composite to be manufactured, and thematerial attenuations are shaped—as is preferred—as passages in thereinforcing structure, the material attenuations form a channel systembetween the covering layers which extends continuously over the entirearea of the reinforcing structure and can accordingly be penetrated bythe joiner parallel to the sheet-like reinforcing structure, such thatthe reinforcing structure is in particular suitable for being filledwith joiner by vacuum injection, wherein the joiner can be injected fromthe side. On the other hand, however, the composite can also bemanufactured by placing the reinforcing structure onto one of thecovering layers, filling the material attenuations with the joiner, andplacing the other of the covering layers onto the reinforcing structure.

In preferred embodiments, the material cells are compacted near thesurface and thus rounded on an upper side or a lower side, along atleast a part of their edges formed by incorporating the materialattenuations. On the one hand, rounding counteracts a notching effectcaused by sharp edges, while on the other hand, the area of the materialattenuations on the upper side or lower side of the reinforcingstructure is increased, which advantageously increases the areaavailable to the joiner for the material connection to the coveringlayers or at least to one of the covering layers and thus increases thestability of the composite.

The cellular material can be compacted in the region of the bridges orthe material cells can be compacted near the surface at ambienttemperature, for example room temperature, or in a heated state of thecellular material. A heatable or non-heatable bridge presser forcompacting the bridges or a heatable or non-heatable top presser forcompacting near the surface, and as applicable for compacting only nearthe edges of the material cells, can be used. If the cellular materialis compacted while warm, it is preferably heated to a temperature justbelow its melting point and compacted at this temperature.

A preferred manufacturing method includes at least one separatingprocess, namely cutting or sawing, and at least one compacting process,namely compacting the cellular material in the region of the bridges oralong the edges of the material cells. In particularly preferred methodembodiments, the material attenuations are incorporated sequentially bycutting and then sawing, and at least the bridges are then compacted;more preferably, both cited compacting processes are performed, forexample firstly compacting the bridges and then compacting at least theedges of the material cells near the surface. A preferred methodtherefore comprises at least three stages, more preferably at leastfour. Proceeding from the cellular base material, the reinforcingstructure is preferably manufactured only by cutting or sawing andadditionally at least one of the two compacting processes.

For incorporating the material attenuations, it is advantageous ifmultiple cutting knives or saw blades are arranged on a cutting tool orsawing tool, facing an upper side of the base material, and are moved,for example pushed, into or preferably through the base material by amovement of the tool towards a lower side of the base material. The term“upper side of the base material” here is merely intended to indicatethe side of the base material facing the cutting knives or saw blades,and is not intended to state whether the separating tool is arrangedvertically above or below the base material, wherein the base materialcan also be processed in a vertical orientation, with the separatingtool then arranged alongside it. If the base material consists ofboards, it expediently lies on a support, and the cutting knives or sawblades are pushed from top to bottom into or preferably through the basematerial.

The cutting knives or saw blades are preferably arranged together ingroups, wherein the cutting knives or saw blades of each grouprespectively produce a material attenuation which—as seen in a topview—is framed by the adjacent material cells and bridges. Within eachof the groups, the cutting knives or saw blades of the respective groupare arranged close to each other in accordance with the shape of thematerial cells and attenuations, respectively. For producing hexagonalmaterial cells, each of the groups consists of three cutting knives orsaw blades which, within each group, are arranged close to each other inaccordance with the angles of the hexagons. In the case of for examplesquare or rhombic material cells, the individual groups would be formedby cutting knives or saw blades arranged crosswise or in the shape of an“X” with respect to each other. In the case of the preferred hexagons,the cutting knives or saw blades of each group are in a Y-shape withrespect to each other, in cross-section; in the case of the particularlypreferred equilateral hexagons, they are each at an angle of 120° toeach other. The cutting knives or saw blades of the individual groupseach cut or saw one limb of the material attenuations. Instead ofarranging separately produced cutting knives or saw blades into groupsof cutting knives or saw blades, the groups can each be formed in onepiece.

Preferably, the cutting knives or saw blades are moved, expedientlypushed, into or through the base material at least substantiallyvertically with respect to the surface forming the upper side of thebase material; the pushing direction is preferably exactly orthogonal tothe surface in question.

In preferred embodiments, the cutting knives or saw blades are onlymoved in a single plane when cutting or sawing, wherein the cutting orsawing movement is a linear movement in preferred embodiments. The sawblades preferably each exhibit a thickness which corresponds to thewidth of the material attenuations. If groups are formed, as ispreferred, then the saw blades of each group form a cross-section whichcorresponds to the cross-section of the material attenuations. In suchembodiments, the saw blades saw into or preferably through the basematerial by means of a linear movement or a movement in one plane only,i.e. they are not moved transverse to their pushing direction relativeto the base material, in order to produce the material attenuations.Incorporating the material attenuations by means of simply moving thecutting knives or saw blades reciprocally in this way expedites thecutting or sawing process. In preferred embodiments, the cutting knivesor saw blades comprise a cutting edge or row of saw teeth which isinclined with respect to the pushing direction. The cutting edge or rowof saw teeth preferably extends up to a tip of each cutting knife or sawblade which protrudes in the pushing direction. The cutting process thusinvolves stabbing and then, while moving the cutting knife in thepushing direction, a cutting engagement with the base material whichcontinues transverse to the pushing direction in the base material. Thesawing process proceeds according to the same pattern, but with a sawingengagement between the saw blade and the cellular material instead ofthe cutting engagement.

When cutting or sawing in batches, the separating tool preferablyperforms a reciprocal stroke movement composed of the pushing movementinto and preferably through the cellular material and the reversemovement.

The separating tool can be fitted with cutting knives or saw blades,preferably groups of cutting knives or groups of saw blades, over itsentire area in accordance with the structuring of the reinforcingstructure to be provided, such that the cutting or sawing process can beperformed in a single stroke for each initial board. In alternativeembodiments, the cutting or sawing tool only comprises a beam or othersupport, from which the cutting knives or saw blades, preferably thegroups of cutting knives or groups of saw blades, project alongside eachother in a row along a line. During a stroke movement, materialattenuations are thus only produced alongside each other on a line, suchthat the separating tool has to be subsequently moved transverse to thesupport relative to the initial board and successively incorporates oneline of material attenuations after the other. Instead of the tool or asapplicable in addition, the initial board can also be moved spatially,in order to incorporate one line of material attenuations after theother.

If the base material is sufficiently flexible that it can be wound ontoa reel even without the material attenuations, then incorporating thematerial attenuations is possible in a continuous method. Suchmaterials, for example PE or PP foams, are unwound in a continuousmethod embodiment from a reel and guided through a roller gap formed bytwo rollers rotating opposite to each other or at least by one rollertogether with a counter-pressure means which is fixed as applicable. Thematerial attenuations are incorporated in the gap. The roller or morepreferably at least one roller of the pair of rollers forming the gap isfitted with the cutting knives or saw blades. The rollers or the rollerand its counter-pressure means which is formed differently co-operate asa male and female mould. In preferred method embodiments, the web issuccessively guided through multiple gaps, preferably through at leasttwo gaps, wherein the male mould of one gap is fitted with cuttingknives and the female mould of the at least one other gap is fitted withsaw blades.

If, as is preferred, the separating process involves at least onecutting process and then at least one sawing process, the base materialis preferably fed automatically to the cutting tool and then to thesawing tool, in a batch operation for example by means of a conveyorbelt or other form of continuous conveying means, and in a continuousprocess as a web product which is conveyed through roller gaps arrangedsequentially in the conveying direction.

In addition to the manufacturing method, the subject of the inventionalso includes a reinforcing structure as such, obtained by means of themethod in accordance with the invention, and also a composite in asandwich construction which comprises at least two covering layers and,between the covering layers, an inserted reinforcing structure of thetype in accordance with the invention, as well as a joiner whichpermeates the reinforcing structure and connects it in a materialconnection to both covering layers, and which is preferably formed by asynthetic resin or an adhesive. The covering layers can in particular beplastic layers or also metal layers, for example light metal layers. Thecomposite can also comprise additional covering layers and additionalreinforcing structures, and can in particular be manufactured in amultiple sandwich construction. A double sandwich comprising threecovering layers, namely an outer, a middle and another outer coveringlayer and two reinforcing structures respectively arranged between theouter covering layers and the middle covering layer, may serve as anexample. It is also possible to arrange one or more reinforcingstructures produced in accordance with the invention, one on top of theother, between covering layers, wherein the lower or lowermostreinforcing structure is adjacent to a lower covering layer, and theupper or uppermost reinforcing structure is adjacent to an uppercovering layer.

Preferred features are also disclosed in the sub-claims and combinationsof the sub-claims.

An example embodiment of the invention is explained below on the basisof figures. Features disclosed by the example embodiment, eachindividually and in any combination of features, advantageously developthe subjects of the claims and also the embodiments described above.There is shown:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 a reinforcing structure in a top view;

FIG. 2 the reinforcing structure in a cross-section;

FIG. 3 the deformed reinforcing structure in a cross-section;

FIG. 4 a cutting knife;

FIG. 4 a a group of cutting knives, in a view from below;

FIG. 5 a saw blade;

FIG. 5 a a group of saw blades, in a view from below;

FIG. 6 a bridge presser;

FIG. 7 a top presser; and

FIG. 8 a composite.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a reinforcing structure made of a cellular material,preferably a plastic foam material. Reinforcing structures, for examplefilaments, can be embedded in the cellular material, however thecellular material is preferably a non-reinforced cellular material. Thereinforcing structure consists of polygonal material cells 1, in theexample embodiment hexagonal material cells 1, and relatively thinconnecting bridges 2. The material cells 1 are connected on each oftheir sides to the nearest adjacent material cell 1 via a centralconnecting bridge 2. Due to their hexagonal shape, each of the materialcells 1 is connected to its nearest adjacent material cells 1 via sixconnecting bridges 2. The width of the material cells 1, as measured ineach direction of the plane of view, is clearly larger than the lengthof the connecting bridges 2. The space between the respectively nearestadjacent material cells 1 is free, apart from the connecting bridges 2.The cavities which thus remain free between the material cells 1 formmaterial attenuations 3 as compared to a non-structured plate-like ormat-like cellular base material. Depending on the bending resistance ofthe plate-like or mat-like base material, these cavities or materialattenuations 3 facilitate—or even at all enable to an appreciableextent—three-dimensional deformability. Primarily, the reinforcingstructure 1, 2 can be three-dimensionally deformed, i.e. bent aboutmultiple axes which do not point parallel to each other, by shifting thematerial cells 1 relative to each other, namely by deforming theconnecting bridges 2. The reinforcing structure 1 is therefore suitableas a core material for three-dimensionally curved lightweight compositesin a sandwich construction. The material attenuations 3 also inparticular enable the penetration of a joiner 17, for example asynthetic resin or adhesive mass, by which two covering layers can befixedly connected to each other in a material connection via thereinforcing structure 1, 2. The joiner 17 preferably completely fillsthe spaces remaining free between the material cells 1 in the region ofthe material attenuations 3 and accordingly forms a honeycombedreinforcing structure for the covering layers in the hardened composite,or if the reinforcing structure 1, 2 is structured differently, formsthis predetermined other reinforcing structure.

FIG. 2 shows the reinforcing structure 1, 2 in a non-deformed initialstate in which the reinforcing structure 1, 2 substantially forms aplanar mat or plate structured in accordance with the shape of thematerial cells 1.

FIG. 3 shows the reinforcing structure 1, 2 in a deformed state in whichnearest adjacent material cells 1 point at an inclined angle to eachother, due to bending in the connecting bridge 2 respectively connectingthem.

The reinforcing structure 1, 2 is produced in batches from a plate-likeor mat-like cellular base material, an initial board, or continuouslyfrom a web material in multiple method steps. The initial board or webproduct exhibits a material thickness which at least substantiallycorresponds to the material cells 1 throughout. It is a homogenous,non-structured board or web material which however exhibits amicroscopic and as applicable also macroscopic cellular structure havinga correspondingly low density. For the example embodiment, it may beassumed that it is a plastic foam material. Such foam materials can inparticular be produced by extrusion and separated into the initialboards to be processed, or can be wound onto a reel as a web product ifthe base material is correspondingly flexible.

The material attenuations 3 are incorporated into such a cellular basematerial in a multi-stage method by cutting and then sawing. Once themulti-stage separating process—which involves at least one cuttingprocess and at least one sawing process—has been completed, theconnecting bridges 2 remaining between the material cells 1 and materialattenuations 3 thus obtained are compacted by compression and theircross-section thus reduced, such that the compacted bridges 2 fall shortof both the upper side and the lower side of the material cells 1, ascan for example be seen in FIGS. 2 and 3. The bridges 2 can be compactedwith or without being heated. Reducing the cross-section of the bridges2 by compression represents a method which is simple and thereforeinexpensive to perform mechanically and which provides contact areas forthe joiner 17 to the respective covering layer of the composite in theregion of the material attenuations 3.

Before the bridges 2 are compacted or more preferably after the bridges2 have been compacted, or as applicable at the same time as the bridges2 are compacted, the material cells 1 are compacted by means ofcompression in a near-surface range of depth on each of the upper sideand lower side, in order to round the edges of the material cells 1which are still sharp-edged after the separating process. In FIGS. 1 to3, the already rounded edges are provided with the reference sign 4. Thematerial cells 1 can also either be heated at least in theirnear-surface range of depth to support compacting this material, or canalso be compacted at ambient temperature, by means of pressure only. Onthe one hand, rounding the edges 4 prevents notching effects and on theother hand advantageously increases the contact area available to thejoiner 17 to the covering layer of the composite situated on therespective upper or lower side of the reinforcing structure 1, 2.

FIGS. 4 and 5 respectively show a cutting knife 5 and a saw blade 7 in alateral view. For incorporating the material attenuations 3, a pluralityof cutting knives 5 are arranged on a cutting tool and an equalplurality of saw blades 7 are arranged on a sawing tool. The cuttingtool can for example be formed by a cutting beam on which the cuttingknives 5 are arranged, projecting from the cutting beam towards the basematerial to be processed. The sawing tool can similarly comprise such asawing beam for the saw blades 7 which are arranged on the sawing beam,projecting towards the base material. The cutting knives 5 and the sawblades 7 are arranged on the respective tool in groups of three, eachconsisting of three cutting knives 5 or saw blades 7 which point in aY-shape with respect to each other, as shown in the views from below inFIGS. 4 a and 5 a. The respective tool can be moved back and forth in apushing direction which is indicated on the cutting knife 5 and sawblade 7 by a directional arrow, such that in the respective strokemovement, the cutting knives 5 of the cutting tool or saw blades 7 ofthe sawing tool are pushed towards and through the base material in thepushing direction. The cutting knives 5 each comprise a tip protrudingin the pushing direction and, inclined from this with respect to thepushing direction—in the example embodiment, inclined at a constantangle of inclination—a cutting edge 6 comparable to a guillotine, suchthat the cutting knives 5 stab into the base material with their tipfirst and then continue to cut through along the respective cutting edge6, in order to obtain an even cut.

The sawing process is performed after cutting, wherein the saw blades 7are positioned exactly opposite the incorporated cuts and then moved inthe plotted pushing direction relative to the initial material providedwith the cuts. The saw blades 7 are moved forwards along the cuts. Theylikewise comprise a tip at their protruding ends in the pushingdirection, comparable to the cutting knives 5, from which a row of sawteeth 8 inclined with respect to the pushing direction tapers offcounter to the pushing direction, comparable to the cutting edge 6. As afirst approximation, the effect of the saw blades 7 is comparable to ajig or sabre saw, however due to the inclined row of saw teeth 8, aforce acting in the pushing direction is sufficient in order to widenthe previously produced cut by a sawing process continuing from therespective tip of the saw blade towards a respectively nearest adjacentconnecting bridge 2 or continuing away from a respectively nearestadjacent connecting bridge 2. During sawing, the material attenuation 3is widened in accordance with the thickness of the saw blades 7, inparticular the thickness of the rows of saw teeth 8.

The cutting knives 5 exhibit a width of preferably at least 300 μm andpreferably at most 800 μm. The saw blades 7 preferably exhibit a largerwidth of preferably at least 400 μm and preferably at most 2 mm.

FIG. 6 illustrates a bridge presser 9 using which one of the bridges 2can be compressed and thus compacted after cutting and sawing, such thatthe cross-section of the bridge 2 in question is permanently reduced. Ona lower side 10, via which it presses against the bridge 2 duringcompression, the bridge presser 9 comprises a central recess 11. Therecess 11 is semi-cylindrical—in the example embodiment, semi-circularcylindrical—and extends over the entire lower side 10. The compactedbridge 2 comes to rest in the recess 11 at the end of the compactingstroke. The bridges 2 are each compressed by means of two bridgepressers 9, one of which faces and opposes the upper side of thereinforcing structure 1, 2 and the other of which faces and opposes thelower side of the reinforcing structure 1, 2. The bridge pressers 9 aremoved towards each other in pairs—as applicable, one of the bridgepressers 9 can remain at rest while only the other one is moved—untilthe bridge 2 in question has been compacted to the desired final shape.The movement direction of the bridge presser 9 is indicated by adirectional arrow. In a preferred embodiment, bridge pressers 9 projectfrom a forming tool in a number and arrangement which corresponds to thenumber and arrangement of the bridges 2 to be compacted. Another suchforming tool is arranged facing the other side of the reinforcingpre-structure produced by cutting and sawing. The bridge pressers 9 eachexhibit a thickness which at least substantially corresponds to thelength of the bridges 2.

FIG. 7 shows a top presser 12 by means of which one of the materialcells 1 is compacted on its upper side or lower side by compression,wherein the material cell 1 is primarily compacted along the edges 4obtained by sawing, wherein the edge 4 in question is primarily rounded.The top presser 12 comprises a hollow space 13 on its lower side facingthe reinforcing structure 1, 2. The hollow space 13 is trough-shaped.During compression, it accommodates the upper or lower side of one ofthe material cells 1. At its circumferential edge, the hollow space 13tapers out in a curve, the shape of which corresponds to the desiredcurve for the edges 4 of the material cells 1. A forming tool isarranged facing each of the upper side and lower side of the reinforcingstructure 1, 2 and is provided with a number of top pressers 12corresponding to the number and shape of the material cells 1. In thisforming step, the material cells 1 are compressed between the toppressers 12 of the two tools and thus compacted near the surface, atleast in the region of the edges 4.

The reinforcing structure 1, 2 can be produced from an initial boardmade of the cellular base material in a batch process as follows:

As already mentioned, the cutting knives 5 are arranged on the cuttingtool along a support of the tool in groups of three cutting knives 5each, wherein the cutting knives 5 of each group of three are arrangedin a Y-shape with respect to each other. The saw blades 7 arecorrespondingly arranged along a support of the sawing tool. Initialboards of the cellular material are conveyed through successively and insteps, below the cutting tool and the sawing tool. In each strokemovement of the cutting tool, the cutting knives 5 produce one cut inthe region of the material attenuations 3 to be provided. The cutregions are then sawn out by means of a stroke movement of the sawingtool and the saw blades 7 projecting from it.

The boards respectively provided after these processes as reinforcingpre-structures are conveyed to the forming tool comprising the bridgepressers 9, where the bridges 2 are compacted. In the final step, theedges 4 of the material cells 1 are rounded by means of another formingtool bearing a plurality of top pressers 12. In a variant, the order ofthe two compacting operations can be reversed. It is also possible tocompact the bridges 2 and round the edges 4 of the material cells 1 atthe same location, and as applicable at the same time. In suchembodiments, a combined forming tool comprises both the bridge pressers9 and the top pressers 12, wherein the bridge pressers 9 can be moved inthe compressing direction relative to the top pressers 12. The bridges 2and material cells 1 can be compacted while cold, at ambienttemperature. In a further development, the bridge pressers 9 aretempered to a temperature slightly below the melting point of thecellular base material. In another further development, the top pressers12 are tempered to such a temperature. It is also possible tocorrespondingly temper the bridge pressers 9 and the top pressers 12.

FIG. 8 shows a composite comprising an upper covering layer 15 and alower covering layer 16, each consisting of a plastic material. Thereinforcing structure 1, 2 is sandwiched between the covering layers 15and 16. The material attenuations 3 are filled with a joiner 17,preferably a hardened resin. The joiner 17 conforms to the honeycombedstructure of the material cells 1 and fills the former materialattenuations 3.

The invention is:
 1. A method for manufacturing a three-dimensionallydeformable, sheet-like reinforcing structure, comprising: incorporatingmaterial attenuations into a sheet-like, cellular base material,distributed over an area of the base material, by cutting or sawing,said material attenuations sub-dividing the base material into aplurality of material cells said material cells delineated from eachother by said material attenuations but are still connected to eachother, wherein the material attenuations are incorporated in such a waythat one or more bridges remain between adjacent material attenuationsand connect adjacent material cells to each other; wherein across-sectional area of said bridges is reduced by compression; whereinsaid bridges are compacted, such that said bridges fall short of anupper side and a lower side of said adjacent material cells: wherein thematerial cells are compacted near the surface and thus rounded on anupper side or a lower side, along at least a part of edges formed byincorporating the material attenuations; and wherein the material cellsare heated at least in the region of the edges to be rounded, and arecompacted near the surface along the heated edges.
 2. The methodaccording to claim 1, wherein the cross-sectional area of the bridges isreduced by heating and compressing the heated bridges.
 3. The methodaccording to claim 1, wherein cutting involves stabbing which preferablypenetrates through the base material.
 4. The method according to claim1, wherein sawing involves jig or sabre sawing which preferablypenetrates through the base material.
 5. The method according to claim1, wherein the material attenuations are incorporated by cutting andthen sawing.
 6. The method according to claim 5, wherein cutting isperformed in a cutting plane, and sawing is performed in the samecutting plane.
 7. The method according to claim 1, wherein the materialattenuations are produced in the base material in the form of recessesor preferably passages, by cutting or sawing.
 8. The method according toclaim 1, wherein cutting is performed using cutting knives or sawing isperformed using saw blades which are only moved in a single cutting orsawing plane when incorporating the material attenuations.
 9. The methodaccording to claim 1, wherein the material attenuations are sawn usingsaw blades which exhibit a thickness which corresponds to a width of thematerial attenuations.
 10. The method according to claim 1, wherein inorder to incorporate the material attenuations, cutting knives of acutting tool or saw blades of a sawing tool facing an upper side of thebase material are moved into or through the base material towards alower side of the base material.
 11. The method according to claim 9,wherein the cutting knives each comprise a cutting edge which isinclined with respect to the movement direction, or the saw blades eachcomprise a row of saw teeth which is inclined with respect to themovement direction.
 12. The method according to claim 11, wherein thecutting knives or saw blades comprise a tip protruding in the movementdirection.
 13. The method according to claim 1, wherein plastic foammaterial is used as the base material, in which reinforcing structuresare optionally embedded.
 14. A method for manufacturing athree-dimensionally deformable, sheet-like reinforcing structure,comprising: providing a base material having an upper surface and alower surface removing portions of said base material from said uppersurface to said lower surface to define a plurality of cellsinterconnected by one or more bridges; compressing said one or morebridges relative to at least one of said upper surface and said lowersurface of said plurality of cells, wherein said one or more bridges areinwardly spaced from at least one of said upper surface and said lowersurface of said plurality of cells; wherein at least some of saidplurality of cells are compacted near said upper surface or said lowersurface and thus rounded on an upper side or a lower side, along atleast a part of edges formed by removing said portions of said basematerial; and wherein at least some of said plurality of cells areheated at least in the region of the edges to be rounded, and arecompacted near said upper surface or said lower surface along the heatededges.
 15. The method according to claim 14, wherein said one or morebridges are compressed relative to each one of said upper surface andsaid lower surfaces of said plurality of cells.